Myself and two other climbers are arriving in Capetown, ZA on the evening of May 29th to spend a month climbing and traveling. We have reservations to stay at the alpha excelsior through the 16th, because one of our team members wants to try and climb some difficult boulders in the Rocklands.

Anyone have any good rental car beta?

Anyone have any first-hand experience with Alpha Excelsior?

Are there other good climbing areas in Western Cape? Preferably some fun, hard, aesthetic, sport crags?

Any help would be greatly appreciated, we are really looking forward to visiting your country and meeting as many climbers as possible!

If you want some sport climbing you should check out Truitjieskraal and surrounds, which is also in the Cederberg region. Other good sport climbing in the Western Cape includes Montagu (1h30min drive from CT) and then the local crags. If its hard sport you are looking for then it would be best to check out the Hole and the Mine.
Needless to say you will have an awesome time in Rocklands. Alpha is good but don't forget to go party down at the campsite bar
There is lots of info on the climbza wiki so you can check out the crags that you wanna head to. If you want to get to an awesome crag (the only limestone in SA) then you should check out Oudsthoorn which is just under a 4hr drive from CT.
Don't forget to check out some of the bouldering in Cape Town. Topside's, Echo Valley would probably be my recommendation.